CN-116259378-B - Method for simulating furnace atmosphere and method for heat-treating metal material

Abstract

The present invention relates to a method of simulating a furnace atmosphere, comprising simulating a change over time in composition of a furnace atmosphere containing at least one of CO and CO 2 when heat treatment of a metallic material is performed in a furnace atmosphere in a heat treatment furnace, wherein the simulation is performed using a mathematical model including the change in composition of the furnace atmosphere, and the change in composition of the furnace atmosphere takes into account the flow rate of gas flowing into the heat treatment furnace, the flow rate of gas flowing out of the heat treatment furnace, and the reaction rate of at least one chemical reaction selected from the group consisting of a gas phase chemical reaction in the furnace atmosphere and a gas phase/solid phase chemical reaction on the surface of the metallic material.

Inventors

• SEN YASHI
• NAKAMURA TAKESHI
• EGUCHI KENJI
• Chai Yuanlu
• YANO KOICHI

Assignees

• 大同特殊钢株式会社
• 国立大学法人三重大学

Dates

Publication Date

20260508

Application Date

20221209

Priority Date

20211210

Claims (9)

1. 1. A method of simulating a furnace atmosphere, comprising simulating a change over time in composition of a furnace atmosphere containing CO and CO 2 when heat treatment of a metallic material is performed in a heat treatment furnace under the furnace atmosphere, Wherein the simulation is performed using a mathematical model comprising the composition change of the furnace atmosphere, and The composition change of the furnace atmosphere takes into account the following factors: The flow rate of the gas flowing into the heat treatment furnace, A flow rate of the gas flowing out of the heat treatment furnace, and The reaction rate of the gas phase chemical reaction in the furnace atmosphere and the gas phase/solid phase chemical reaction on the surface of the metal material, The reaction rate of the chemical reaction is represented by a modified arrhenius equation represented by the following formula (a): Wherein k f (T) is a reaction rate constant at a temperature T, k' f is a frequency factor, T is a temperature in the heat treatment furnace, b is a constant, E f is an activation energy, and R is a gas constant, At least one of the flow rate of the gas flowing into the heat treatment furnace and the reaction rate of the chemical reaction includes an error function, wherein the error function of the flow rate of the gas flowing into the heat treatment furnace takes into account a contribution by the error of the flow rate of the gas flowing into the heat treatment furnace, the error function of the reaction rate of the chemical reaction takes into account a contribution by the reduction of an oxide other than FeO, The metal material is Fe or an Fe-based alloy, and the equilibrium reaction represented by the following formulas (1) to (7) or the following formulas (1) to (9) is regarded as the chemical reaction, and Simulation was performed by incorporating an increase or decrease in the concentration of each gaseous component contained in the furnace atmosphere with time, which is caused by the following equilibrium reaction,
2. 2. The method for simulating an atmosphere in a furnace according to claim 1, Wherein the gas flowing into the heat treatment furnace and the gas flowing out of the heat treatment furnace include: An inflow gas for increasing the carbon potential factor of the furnace atmosphere, An inflow gas for reducing the carbon potential factor of the furnace atmosphere, and And the whole exhaust gas of the furnace atmosphere.
3. 3. The method for simulating an atmosphere in a furnace according to claim 1, Wherein the change in composition of the furnace atmosphere over time comprises a change in concentration of CO or CO 2 over time.
4. 4. The method of modeling a furnace atmosphere as claimed in claim 1, wherein only a reaction rate of the chemical reaction includes the error function.
5. 5. The method for simulating an atmosphere in a furnace according to claim 1, Wherein the reaction rates of the chemical reactions of formulae (6) and (7) each comprise an error function.
6. 6. The method for simulating an atmosphere in a furnace according to claim 5, Wherein error functions are included by adding error coefficients Delta CO 、Δ CO2 、Δ H2 and Delta H2O to the rates of change of the concentrations of CO, CO 2 、H 2 and H 2 O in the heat treatment furnace, respectively, Wherein the error coefficients have the relationship of Delta CO ＝-Δ CO2 and Delta H2 ＝-Δ H2O , and Where Δ CO2 and Δ H2O are each functions that cause positive values to decrease over time and converge to zero.
7. 7. The method of simulating an atmosphere in a furnace according to claim 1, further comprising determining an unknown parameter contained in the mathematical model by comparing a simulation result of a change over time in concentration of at least one of CO and CO 2 with an actual inspection result in an actual heat treatment furnace.
8. 8. The method of simulating an atmosphere in a furnace according to claim 7, wherein the mathematical model includes a plurality of unknown parameters, and values of the unknown parameters are determined in descending order of influence on the simulation result.
9. 9. A method of heat-treating a metal material, comprising controlling a flow rate of a gas flowing into the heat treatment furnace and a flow rate of a gas flowing out of the heat treatment furnace based on a simulation result obtained by the method of simulating an atmosphere in a furnace according to any one of claims 1 to 8 when the metal material is heat-treated in an actual heat treatment furnace.

Description

Method for simulating furnace atmosphere and method for heat-treating metal material Technical Field The present invention relates to a method of simulating a furnace atmosphere and a method of heat treating a metallic material. More specifically, the present invention relates to a method for simulating the composition of a furnace atmosphere for heat treatment of a metal material, and to a method for controlling a furnace atmosphere in heat treatment of a metal material using simulation results obtained by the method. Background When a metal material including steel is heat treated to temper it, decarburization, carburization and oxidation of the metal material often occur. The progress of these phenomena depends on the composition of the atmosphere in the heat treatment furnace. Therefore, in order to suppress the progress of these phenomena or to adjust the progress thereof to a desired extent and thereby adjust the composition and properties of the steel, control of the furnace atmosphere is performed. In the case of controlling decarburization and carburization, an endothermic modifying gas (RX gas) containing CO, H 2 and N 2 is generally used to adjust the furnace atmosphere. In the case of controlling the furnace atmosphere using a gas containing CO or CO 2 and an RX gas, a carbon Potential Factor (PF) is generally used as an index for controlling the atmosphere. PF is an index value of carbon potential and is calculated by PF= [ CO ] 2/[CO2 ] where [ CO ] and [ CO 2 ] are the CO concentration and CO 2 concentration in volume% in the furnace, respectively. The greater the PF value, the more carburization proceeds, while the smaller the PF value, the more decarburization proceeds. Accordingly, a target value of the PF is set according to the desired carbon concentration of the metal material, and feedback control, such as PID control, is performed while monitoring the CO concentration and the CO 2 concentration in the furnace atmosphere so as to bring the actual PF value of the furnace atmosphere close to the target value. Accordingly, the gas flowing into the furnace and the gas flowing out from the furnace are controlled, such as RX gas flowing into the furnace, N 2 gas flowing in for safety (for ensuring furnace pressure to prevent explosion caused by air entering the furnace), N 2 gas and/or air flowing in for reducing PF, and discharged furnace atmosphere gas. For example, patent document 1 discloses a method for controlling a furnace atmosphere using a PF value as an index. [ Patent document 1] JP-A-H2-153017 Disclosure of Invention In the interior of a heat treatment furnace for heat-treating a metal material, a plurality of chemical reactions occur, which affect the concentrations of the constituent components of the furnace atmosphere including CO and CO 2, and the heat treatment is performed in a state where these reactions are associated with each other. Thus, the furnace atmosphere may undergo complex or abrupt changes. However, in the case where the CO concentration and the CO 2 concentration in the furnace atmosphere are monitored to calculate the PF value and the furnace atmosphere is controlled by feedback control, there may be a case where the control of the furnace atmosphere cannot quickly follow the actual change of the furnace atmosphere. This makes it difficult to properly control the carbon concentration of the metal material. Particularly in the case where a gas phase/solid phase reaction such as reduction of surface oxides (oxide scale) of a metal material has a large contribution, control of the furnace atmosphere based on the PF value of the atmosphere cannot sufficiently follow the actual change of the furnace atmosphere. As a basis for high-precision control of the furnace atmosphere, a technique of highly accurately simulating how the composition of the furnace atmosphere changes during the course of heat treatment is desired. An object of the present invention is to provide a furnace atmosphere simulation method capable of highly accurately simulating a change in the furnace atmosphere of a heat treatment furnace with the progress of heat treatment in heat treatment of a metal material that can undergo decarburization and carburization, and to provide a metal material heat treatment method capable of utilizing the simulation result. In order to solve the above-described problems, the present invention relates to the following configurations [1] to [12]. [1] A method of simulating a furnace atmosphere, comprising simulating a change over time in composition of a furnace atmosphere containing at least one of CO and CO 2 when heat treatment of a metallic material is performed in a heat treatment furnace under the furnace atmosphere, Wherein the simulation is performed using a mathematical model comprising a change in composition of the furnace atmosphere, and The composition change of the furnace atmosphere takes into account the following factors: The flow rate (rate of ga